Under which condition is phosphofructokinase inhibited?

Under which condition is phosphofructokinase inhibited?

• A. When ATP is plentiful
• B. When ATP is depleted
• C. In the presence of high AMP
• D. During fasting

Answer: (A)

PFK-1 acts as the energy sensor for glycolysis. When ATP is plentiful, ATP binds to an allosteric site on PFK-1 and inhibits its activity, slowing the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate. This prevents unnecessary glycolysis when the cell already has enough energy. In contrast, low energy states raise AMP/ADP, relieving the inhibition and activating PFK-1 to boost glycolysis. High AMP serves as an activator, not an inhibitor, and fasting doesn't directly cause PFK-1 inhibition. So the condition that inhibits PFK-1 is abundant ATP.

PFK-1 acts as the energy sensor for glycolysis. When ATP is plentiful, ATP binds to an allosteric site on PFK-1 and inhibits its activity, slowing the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate. This prevents unnecessary glycolysis when the cell already has enough energy. In contrast, low energy states raise AMP/ADP, relieving the inhibition and activating PFK-1 to boost glycolysis. High AMP serves as an activator, not an inhibitor, and fasting doesn't directly cause PFK-1 inhibition. So the condition that inhibits PFK-1 is abundant ATP.